Notices
Gas Engines Questions or comments about gas engines can be posted here

Sachs dolmar

Old 03-18-2020, 12:08 PM
  #26  
Truckracer
My Feedback: (19)
 
Join Date: Apr 2004
Location: Des Moines, IA
Posts: 5,256
Received 37 Likes on 37 Posts
Default

Originally Posted by CK1 View Post
Lee , I would apply some heat to the hub it's either corroded to the crank or it has loctite on it . In either case the heat should help.
+1 on the Loctite. Probably red so it will need some heat.
Old 03-18-2020, 05:45 PM
  #27  
rclbsimmo
My Feedback: (4)
 
Join Date: Aug 2005
Location: , IN
Posts: 47
Likes: 0
Received 1 Like on 1 Post
Default

OK, got it off....just needed to put it in vise, get my buddy to help and we got it loose, no heat required....it's just a nut...std threads.
Now I need to get a longer one made....I'll use 6061 T6 1.75" round rod and have it machined locally.
Thanks guys.....
Old 03-18-2020, 06:16 PM
  #28  
Truckracer
My Feedback: (19)
 
Join Date: Apr 2004
Location: Des Moines, IA
Posts: 5,256
Received 37 Likes on 37 Posts
Default

Just curious ..... how many threads were engaged in the hub? The one I worked on only had like 3 or 4 threads and I was amazed that anyone would leave an engine like that. Also made me wonder about safety after I had previously stood in front of that engine during starts on many occasions.

Sometimes it can be difficult to make a longer hub run true. It all depends on the mating surface and of course the accuracy of the machining.
Old 03-27-2020, 05:36 AM
  #29  
rclbsimmo
My Feedback: (4)
 
Join Date: Aug 2005
Location: , IN
Posts: 47
Likes: 0
Received 1 Like on 1 Post
Default

When I screw the hub on...I turn it 7 revs until it stops....
But it looks like more would be better....I hope it stays on....Must be OK as haven't heard any coming off?? But that's an older engine.

Last edited by rclbsimmo; 03-27-2020 at 09:49 AM.
Old 08-02-2021, 08:29 AM
  #30  
JohnVH
My Feedback: (38)
 
JohnVH's Avatar
 
Join Date: Dec 2001
Location: Ferndale, WA
Posts: 16,174
Received 9 Likes on 7 Posts
Default

Looking for a little help on my 4.2, I can adjust the needles so full throttle is great, idle is great, half throttle isnt burbly and runs great, but when I let it idle for 5 seconds and punch it fast, itll die... If I move the throttle stick a little slower, itll be ok, is that normal? Or do I have something else wrong? Thanks



Old 08-02-2021, 09:33 AM
  #31  
CK1
My Feedback: (60)
 
CK1's Avatar
 
Join Date: Apr 2002
Posts: 1,550
Likes: 0
Received 24 Likes on 17 Posts
Default

It's possible you're a bit lean on the low end and a little rich on the high end . Getting the top end peaked just right and not overly rich will help to get a good mid range without burble and a reliable transition from idle to WOT. BTW... what prop size are you using ?
Old 08-02-2021, 09:37 AM
  #32  
JohnVH
My Feedback: (38)
 
JohnVH's Avatar
 
Join Date: Dec 2001
Location: Ferndale, WA
Posts: 16,174
Received 9 Likes on 7 Posts
Default

Originally Posted by CK1 View Post
It's possible you're a bit lean on the low end and a little rich on the high end . Getting the top end peaked just right and not overly rich will help to get a good mid range without burble and a reliable transition from idle to WOT. BTW... what prop size are you using ?
Ive gone from too rich (shown in video below, listen to it at part throttle, burbling like crazy, sucking alot of gas!) to too lean to try to fix it.. Ive never had an engine I couldnt get right, except for this one, so Im wondering what the nature of the beast is.

Old 08-02-2021, 10:03 AM
  #33  
CK1
My Feedback: (60)
 
CK1's Avatar
 
Join Date: Apr 2002
Posts: 1,550
Likes: 0
Received 24 Likes on 17 Posts
Default

I just went through this same issue recently on a Hellcat with a Brison 4.2 . Same exact issues as yours . I've ran into this on a couple others as well . The resolution for the issue was to first rebuild the carb . The diaghragm were a little stiff and the inlet needle was not seating . The pop off pressure before the rebuild would vary from 10 psi to over 35 psi on multiple pop off tests . Rebuilding the carb made things much much better but it still went a little rich at flying speed but not on the ground . To solve this a static vent line was added to the carb diaghram plate .A line from the diaghragm plate into the fuselage . This stabilized the pressure differential and solved the going rich flying at speed . A further note is that the 4.2 engine with the SDC 80 seems to need the high needle to be set to peak rpm's and no more and the low needle to be set just rich enough to where it's bordering on a lean hesitation plus about 10 degrees rich on the needle rotation once the engine is warmed up .
This should give you few things to consider but I also would check the ignition timing and set it to 28 btdc
Old 08-02-2021, 10:08 AM
  #34  
JohnVH
My Feedback: (38)
 
JohnVH's Avatar
 
Join Date: Dec 2001
Location: Ferndale, WA
Posts: 16,174
Received 9 Likes on 7 Posts
Default

Where would I find a carb rebuild kit?
Old 08-02-2021, 10:50 AM
  #35  
CK1
My Feedback: (60)
 
CK1's Avatar
 
Join Date: Apr 2002
Posts: 1,550
Likes: 0
Received 24 Likes on 17 Posts
Default

https://www.jackssmallengines.com/ja...iversal/615534
Old 08-02-2021, 10:52 AM
  #36  
CK1
My Feedback: (60)
 
CK1's Avatar
 
Join Date: Apr 2002
Posts: 1,550
Likes: 0
Received 24 Likes on 17 Posts
Default

https://www.ebay.com/sch/i.html?_nkw...id=m5467.l1311
Old 08-02-2021, 10:52 AM
  #37  
Truckracer
My Feedback: (19)
 
Join Date: Apr 2004
Location: Des Moines, IA
Posts: 5,256
Received 37 Likes on 37 Posts
Default

+1 on CK1ís usual good advice. The Walbro SDC repair kit is available from any good lawn, yard equipment and chainsaw store. Widely available from a number of eBay vendors also. There is only one Walbro SDC repair kit for all the various SDC carb numbers. I highly recommend you get a genuine Walbro kit but if you canít find that, Stens or Oregon kits are ok too. Donít buy one of the cheap Chinese knock off kits.

Old 08-02-2021, 10:54 AM
  #38  
CK1
My Feedback: (60)
 
CK1's Avatar
 
Join Date: Apr 2002
Posts: 1,550
Likes: 0
Received 24 Likes on 17 Posts
Default

Be sure to replace the inlet needle valve . The tips get distorted over time and will cause pop off pressure issues which will cause tuning difficulties
Old 08-02-2021, 11:53 AM
  #39  
Truckracer
My Feedback: (19)
 
Join Date: Apr 2004
Location: Des Moines, IA
Posts: 5,256
Received 37 Likes on 37 Posts
Default

The SDC 80 may also have two different sized metering needles depending on the age of the carb. Both are supplied in the kit. Iíve found the carbs with the small needles seem to tune a bit easier and are less affected by ďGĒ forces in flight. Either version works fine overall. If I ever had a complaint about the SDC 80 it would be that delicate balance between the high and low speed needle settings. More than most Walbro carbs.
Old 08-02-2021, 12:28 PM
  #40  
JohnVH
My Feedback: (38)
 
JohnVH's Avatar
 
Join Date: Dec 2001
Location: Ferndale, WA
Posts: 16,174
Received 9 Likes on 7 Posts
Default

Ok, Ill order a kit up, hope that does it, the engine runs perfect, other than advancing the throttle too fast makes it bog out

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.